Tectonophysics (2003) v. 375, p. 5 – 7

Chris Powell was born in Guildford, Surrey on 28 April 1943. He arrived in Australia from England in 1949 and completed his secondary education by correspondence while working on his family cattle property near Clermont in central Queensland. He gained a scholarship to the University of Queensland, where he graduated with first class honours in Geology in 1964. Moving to the University of Tasmania, he studied under the supervision of Professor S.W. Carey and was awarded his PhD degree in 1968. With such a background, it is no surprise that he developed an expertise in structural geology and tectonics. His first appointment was as NASA Post-doctoral Fellow at Northwestern University, Chicago during 1967/1968. It was here that he met and married his wife Rosemarie. He then served as an Assistant Professor in Geology at the University of Cincinnati, OH (1968–1970). Returning to Australia in 1970, he was appointed Lecturer in Earth Sciences at Macquarie University, Sydney. During a 20-year stay at Macquarie, he rose to the rank of Associate Professor (1979) and became Head of the School of Earth Sciences (1987–1989).

In 1990, he was appointed Professor of Geology at the University of Western Australia. While in the USA, Chris was able to reinforce his skills in structural analysis in field regions such as Montana and the Appalachians. One of his major contributions to structural geology is in the origin of natural rock fabrics. His work on cleavage during non-coaxial strain led to the concept of transected fields, in which cleavage formed during folding cut from one limb to another. The book Atlas of Deformational and Metamorphic Rock Fabrics (Borradaile, Bayly and Powell, Springer-Verlag, 1982) covered the whole range of such fabrics. Subsequently, Chris developed a morphological classification of cleavages that is now in wide use in most textbooks on structural geology. During his early years at Macquarie University, he went on two major expeditions to the Himalayas. This and subsequent work led him, with Conaghan in 1973, to propose that the uplift of the Tibetan plateau was not a direct result of continent–continent collision, as was widely believed, but was due to the underthrusting of the Indian continental crust beneath the Eurasian crust. Later, in 1986, Chris modified this model from continental underthrusting to continental underplating. The high elevation of Tibet is thus a geologically relatively recent response to isostatic adjustment of two continental crusts. At a Penrose Conference on Tibet in 1977, Chris used the evolution of the Indian Ocean to position India in times past and show that the shape of peninsular India plus the Tibetan plateau matched the shape of Greater India. As a result, the timing of the collision of India with Asia was a lot earlier than the ~40 Ma date then commonly assumed. In 1974, Chris discovered that there was an anomaly in the then current tectonic synthesis of the Lachlan Fold Belt, when he found that the main regional deformation postdated the Upper Devonian Lambie Group. This was contrary to existing opinion and he then showed that this discovery held up on a wide regional scale. He found the first evidence of an early fold system oblique to the younger N-trending structures. This led to his increasing awareness of the inadequacy of existing models of the Belt, especially the confusion of structural and stratigraphic trends by authors. Perhaps one of his most significant contributions to an understanding of the Lachlan Fold Belt has been through the combination of linked palaeocurrent and provenance studies to the Devonian quartzose clastics in both terrestrial and shallow marine environments and in deep marine turbidite facies. By combining regional basin analysis with an understanding of when various structures formed, he was able to present an integrated synthesis of the history of the Tasman Fold Belt.

One of his discoveries of potentially much wider significance was that there is a series of mid-Carboniferous megakinks formed under compression at the same time as major overthrusts and folds were forming in central Australia. This was one of the first links established between the deformational history of the Tasman Fold Belt and that of the western two-thirds of Palaeozoic Australia, probably related to global orogenesis in the mid-Carboniferous. At least 15 years ago, Chris realised that, in order to test global tectonic reconstructions, one had to combine palaeomagnetism with regional geology. Together with Z.X. Li, he established that the first amalgamation of Gondwana did not occur until the Cambrian. He played a major role in documenting the Devonian to Early Carboniferous track of the South Pole across Gondwana into central Africa. This has important consequences for the timing of the collision of Gondwana and Laurussia, which is shown to be a mid-Carboniferous event, not Late Devonian. In 1993, Chris and co-workers showed from the then available palaeomagnetic data that Australia and Laurentia were probably adjacent in a Rodinia reconstruction, which broke up about 725 Ma to form the Pacific Ocean. After Rodinia broke up, he proposed that there existed a late Precambrian supercontinent he named Pannotia that lasted only a few million years between 580 and 550 Ma. This interest in global tectonic reconstructions led him to apply for the establishment of a Special Research Centre at the University of Western Australia. He proposed a 9-year program to discover the supercontinents of which Australia has been a part in the past 3 billion years and the processes that formed them. In 1997, he was awarded one of the first 8 of such centres out of 90 initial applications. The Tectonics Special Research Centre (TSRC) was thus formed with nodes at the Curtin University of Technology in Perth and the University of Texas at Austin.

As Director of the TSRC Chris lived on a new high. He travelled widely to all the leading conferences enthusiastically presenting new findings from research at the Centre. As a result, he established the TSRC as the world's leading research centre in global tectonics. He enticed top ranking young scientists to come as Post-doctoral Fellows. Eminent scientists from around the world came to work at the Centre on short and longer visits, contributing to the program and interacting with students and staff. Work at the Centre covered many dimensions ranging from studying the collision zone between west and east Gondwana in Madagascar to trying to discover the reconstruction of Rodinia of which Australia is presumed to be a central part. The reports on the current program at the Centre provide the details of the enormous amount of work that is about to be completed. During the first 5 years, 170 research papers have been published by staff, students and visitors to the Centre. This is a record that relates to Chris's dynamic leadership and scientific vision. Chris published more than 120 papers in the world's leading scientific journals. Several of these were still in press at the time of his death. He will be remembered not only as an outstanding scientist and leader, but also as a man of passion, enthusiasm and boundless energy. To many he was also a forthright and generous friend, to his students an inspiring and patient teacher, to his family a loving father and husband. He died suddenly on 21 June 2001, while on a flight from Johannesburg to London, after participating in a successful field excursion in South Africa. He was on his way to attend a field symposium in Irkutsk, looking forward to seeing Siberia for the first time. The TSRC will miss his inspiration and leadership and he will be a hard act for anyone to follow.

M. McElhiny

Gondwana Consultants

31 Laguna Place

Port Macquarie, NSW 2444

Australia